What event in 1968 prompted anti-war protests to increase throughout the united states

Why is it useful for historians to base certain studies on the analysis of historical periods

In relation to the september 11th attacks, the term ground zero refers to new york city. the pentagon. the shanksville, pennsylvania, memorial. the site of the world trade center.r

What did the u.s. want to build on the land acquired through the gadsden purchase?